title: Pioglitazone protects the myocardium against ischemia-reperfusion injury in eNOS and iNOS knockout mice.
abstract: Endothelial nitric oxide synthase (eNOS) activation with subsequent inducible NOS (iNOS), cytosolic phospholipase A2 (cPLA2), and cyclooxygenase-2 (COX2) activation is essential to statin inhibition of myocardial infarct size (IS). In the rat, the peroxisome proliferator-activated receptor-gamma agonist pioglitazone (Pio) limits IS, upregulates and activates cPLA2 and COX2, and increases myocardial 6-keto-PGF1alpha levels without activating eNOS and iNOS. We asked whether Pio also limits IS in eNOS-/- and iNOS-/- mice. Male C57BL/6 wild-type (WT), eNOS-/-, and iNOS-/- mice received 10 mg.kg(-1).day(-1) Pio (Pio+) or water alone (Pio-) for 3 days. Mice underwent 30 min coronary artery occlusion and 4 h reperfusion, or hearts were harvested and subjected to ELISA and immunoblotting. As a result, Pio reduced IS in the WT (15.4+/-1.4% vs. 39.0+/-1.1%; P<0.001), as well as in the eNOS-/- (32.0+/-1.6% vs. 44.2+/-1.9%; P<0.001) and iNOS-/- (18.0+/-1.2% vs. 45.5+/-2.3%; P<0.001) mice. The protective effect of Pio in eNOS-/- mice was smaller than in the WT (P<0.001) and iNOS-/- (P<0.001) mice. Pio increased myocardial Ser633 and Ser1177 phosphorylated eNOS levels in the WT and iNOS-/- mice. iNOS was undetectable in all six groups. Pio increased cPLA2, COX2, and PGI2 synthase levels in the WT, as well as in the eNOS-/- and iNOS-/-, mice. Pio increased the myocardial 6-keto-PGF1alpha levels and cPLA2 and COX2 activity in the WT, eNOS-/-, and iNOS-/- mice. In conclusion, the myocardial protective effect of Pio is iNOS independent and may be only partially dependent on eNOS. Because eNOS activity decreases with age, diabetes, and advanced atherosclerosis, this effect may be relevant in a clinical setting and should be further characterized.
authors.affiliation: Department of Biochemistry and Molecular Biology, Graduate School of Biomedical Science, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Yumei
authors.initials: Y
authors.lastname: Ye
authors.forename: Yu
authors.initials: Y
authors.lastname: Lin
authors.forename: Saraswathy
authors.initials: S
authors.lastname: Manickavasagam
authors.forename: J Regino
authors.initials: JR
authors.lastname: Perez-Polo
authors.forename: Brian C
authors.initials: BC
authors.lastname: Tieu
authors.forename: Yochai
authors.initials: Y
authors.lastname: Birnbaum
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000818:Animals; D002317:Cardiovascular Agents / Q000494:pharmacology*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004195:Disease Models, Animal; D015151:Immunoblotting; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency* / Q000235:genetics; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency* / Q000235:genetics; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism; D010766:Phosphorylation; D000077205:Pioglitazone; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D045162:Thiazolidinediones / Q000494:pharmacology*
chemical_list: D002317:Cardiovascular Agents; D012333:RNA, Messenger; D045162:Thiazolidinediones; D015121:6-Ketoprostaglandin F1 alpha; D003577:Cytochrome P-450 Enzyme System; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496317:Nos2 protein, mouse; C496315:Nos3 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D054510:Phospholipases A2, Cytosolic; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase; D000077205:Pioglitazone